<template>
    <div class="pagination">
        <!-- 首 -->
        <button :disabled="pageNo==1" @click="$emit('getPageNo',pageNo-1)">上一页</button>
        <button 
        v-if="startNumAndEndNum.start>1" 
        @click="$emit('getPageNo',1)" 
        :class="{active:pageNo==1}"
        >1</button>
        <button v-if="startNumAndEndNum.start>2">...</button>
        <!-- 中间部分 -->
        <button 
        v-for="(page,index) in startNumAndEndNum.end" 
        :key="index" 
        v-if="page>=startNumAndEndNum.start"
        @click="$emit('getPageNo',page)"
        :class="{active:pageNo==page}"
        >{{page}}</button>
        <!-- 尾巴 -->
        <button v-if="startNumAndEndNum.end<totalPage-1">···</button>
        <button 
        v-if="startNumAndEndNum.end<totalPage" 
        @click="$emit('getPageNo',totalPage)"
        :class="{active:pageNo==totalPage}"
        >{{totalPage}}</button>
        <button :disabled="pageNo==totalPage" @click="$emit('getPageNo',pageNo+1)">下一页</button>

        <button style="margin-left: 30px">共 {{total}} 条</button>
    </div>
</template>

<script>
export default {
   name:'Pagination',
   props:['pageNo','pageSize','total','continues'],
   data() {
      return {
      }
   },
   created(){
   },
   computed:{
       totalPage(){
        //向上取整
           return Math.ceil(this.total/this.pageSize)
       },
       startNumAndEndNum(){
           let start = 0, end = 0
        //连续页码至少5页 
            if(this.continues>this.totalpage){
                start = 1
                end = totalPage
            }else{
                start = this.pageNo - parseInt(this.continues/2)
                end = this.pageNo + parseInt(this.continues/2)
                // 头
                if(start<=0){
                    start = 1
                    end = this.continues
                }
                // 尾巴
                if(end>this.totalPage){
                    start = this.totalPage - this.continues + 1
                    end = this.totalPage
                }
            }
            return {start,end}
       }
   },
   methods:{
   },
}
</script>

<style lang='less' scoped>
    .pagination {
        button {
            margin: 0 5px;
            background-color: #f4f4f5;
            color: #606266;
            outline: none;
            border-radius: 2px;
            padding: 0 4px;
            vertical-align: top;
            display: inline-block;
            font-size: 13px;
            min-width: 35.5px;
            height: 28px;
            line-height: 28px;
            cursor: pointer;
            box-sizing: border-box;
            text-align: center;
            border: 0;

            &[disabled] {
                color: #c0c4cc;
                cursor: not-allowed;
            }

            &.active {
                cursor: not-allowed;
                background-color: #409eff;
                color: #fff;
            }
        }
    }
</style>
